The 3GPP (3rd Generation Partnership Project) has two separate tracks developing a new standard for the Internet of Things (IoT) of Machine Type communications, in which everyday objects are provided with network connectivity. The first track is an LTE (Long Term Evolution) track referred to as MTC (Machine Type Communications) and the second track is a GERAN (GSM (Global System for Mobile Communications)/EDGE (Enhanced Data-rates for Global Evolution) Radio Access Network) track referred to as NB IOT (Narrow Band Internet of Things) formerly known as IoT (Internet of Things). Versions of both tracks address the need for range extension and/or enhanced coverage. 3GPP plans to achieve enhanced coverage with repetitions of transmission, referred to within 3GPP as Coverage Enhancement (CE), and plans to support various CE-levels (e.g., 15 dB enhancements divided into 6 levels). Such CE may be necessary in situations where the UE is beyond normal cell boundaries, such as when located in a below-ground basement of a building.
Current methodologies for CE provide for the base station (i.e., eNB) and the UE (i.e., mobile terminal) to decide on CE-level while being in connected mode. Specifically, when the UE is entering the idle mode, the base station/eNB informs the Mobile Management Entity (MME) which CE-level was used during the connected mode. Thus, current methodologies assume that the CE-level that is stored by the MME will be the CE-level during paging (i.e., while the UE is in idle mode). However, current methodologies are silent as to how the CE-level stored in the MME can be updated during idle mode. Such updating of the CE-level during idle mode is necessary to insure that a MTC/NB IoT device is successfully paged and, in the event the MTC/NB IoT device has better radio conditions, the cellular network benefits from being able to save paging resources (i.e., CE may no longer be required, or a lower CE level may be used).
Typically, when the UE is in idle mode, it periodically listens to cell broadcast signals from a base station logically connected with it. These broadcast signals may provide information such as cell or eNB identification. The UE is also required to listen for specific paging information, such as incoming downlink traffic to the specific UE. However, in the case of uplink traffic initiation, the UE must take initiative to notify the base station regarding its intention to transfer data. This procedure is known as random access.
The random access procedure or mechanism is the mechanism by which the UE pages the eNB to initiate uplink data transfer. Within the random access procedure, the UE sends a specific random access message (or preamble) to the eNB. The timing for the random access message allowed to be sent from the UEs is typically determined by the eNB broadcast system information.
When the UE is an idle mode, the UE takes measurements from the broadcast signal received from the base station. These measurements are typically made during paging occasions. Such occasions occur when the UE must listen for potential network initiated traffic. Based on the measurements, the UE selects a suitable CE level for potential UE-initiated connection setup. Therefore, when the UE initiates the random access mechanism, the UE has already selected a CE level that it believes is suitable.
In some cases, however, the random access message is not received by the eNB or is not discernable by the eNB. Thus, a need exists for improving the random access mechanism.